Novel, validated methods to monitor adherence to HIV treatment in real time are urgently needed given the well-known limitations of self-reported adherence, pill counts, and medication electronic monitoring system (MEMS) caps. In order to be scalable and sustainable in both resource-rich and resource limited settings, such devices need to be low-cost and designed in a way that does not increase the risk of accidental HIV disclosure and subsequent stigma. Devices which both monitor adherence in real time and provide tailored reminders to patients for medication-taking have the potential to greatly improve adherence to HIV treatment as well as to treatment for other chronic diseases. Our Indo-US collaborative team has been conducting research on HIV stigma, ARV adherence patterns and barriers, treatment outcome, and drug resistance for over a decade. We have also pioneered the use of ARV concentrations in small hair samples to measure long-term ARV adherence in resource-rich and limited settings (RLS). In response to the need for novel adherence meaures, our team has recently developed Tel-Me-Box, a small, low-cost adherence device that monitors adherence in real time, by transmitting a wireless signal to a server when opened. We now propose to add hardware that will enable the server software to wirelessly program the device to activate tailored medication-taking reminders (via a beep, vibration, or LED light) after a period of inactivity. The device fits in a pocket, can hold 1-2 weeks' worth of medications, has a long battery life, simple charging capability, and has been found acceptable to Indian patients with adherence challenges in pilot studies. Since HIV stigma serves as a profound barrier to ARV adherence in many settings, including India, the small, inconspicuous nature of Tel-Me-Box, along with its ability to deliver tailored reminder features honors participants' privacy concerns. Since this electronic device monitoring cannot assess actual drug ingestion, validating it against a biological measure of adherence, such as ARV hair concentrations, is crucial. This study has the following 3 aims: Aim 1 will further refine Tel-Me-Box by reducing its size and adding tailored reminder features. We will also demonstrate feasibility of hair analysis in RLS by training local staff to conduct the relevant hair assays. Aim 2 will validate the Tel-Me-Box adherence measure, using ARV hair concentrations and HIV viral load, and examine the predictive utility of Tel-Me-Box monitoring and hair drug levels on virologic suppression in HIV- infected patients. In Aim 3, we will conduct a pilot RCT to examine acceptability and feasibility and to estimate the effect size of automated tailored real-time adherence reminders on hair ARV concentrations, device- monitored adherence, and viral load suppression in adherence-challenged patients. At study completion, we expect to have validated Tel-Me-Box as an innovative tool to assess adherence and predict treatment outcomes and demonstrated the feasibility of hair analyses in RLS. If successful, we will also have collected pilot data on the efficacy of the Tel-Me-Box automated, tailored reminders for a future large scale RCT.